The statistical comparison of reproduction rates for groups of sheep

Abstract

Statistical tests based on the chi-squared distribution are given for testing the homogeneity of lambing rates (the number of lambs born per ewe joined) and foetal survival rates. The inadequacy of a traditional chi-squared statistical test for testing the hypothesis of complete homogenity between groups, is pointed out, and the calculations illustrated with numerical examples. A comparison with the analysis of variance is also made.